A kind of totally-enclosed symmetric packages lead frameTechnical field
The present invention relates to electronic technology fields, more particularly to a kind of totally-enclosed symmetric packages lead frame.
Background technique
Currently, traditional SOP/SOIC and TSOP series encapsulation generallys use the packing forms of total incapsulation, that is, use plastic packaging materialThe pyrotoxin and carrying substrates of integrated circuit are all encapsulated.Firstly, on the one hand this traditional package cooling approach isIt is conducted by connecting wire, pin；On the other hand it is radiated by ontology plastic packaging material to surrounding.Due to the pin of this kind encapsulationSmall in size, ontology plastic packaging material pyroconductivity is again big compared with small and packaging body, so the thermal energy that integrated circuit operation generates cannot be realExisting good conduction, is concentrated mainly on the inside of packaging body, heat dissipation effect is not ideal enough, and service life is short.According to statistics, electricity is integratedThe failure majority on road is caused by cannot timely and effectively being conducted by heat.With the hair of semiconductor direction micromationExhibition, integrated level is higher and higher, and with regard to more and more, such integrated circuit is operating the number of the transistor integrated in integrated circuitWhen, calorific value is with regard to increasing, and the reliability that excessively high temperature will cause integrated circuit reduces and performance decline, in circuit applicationThere are unstable factors, and integrated circuit is even burnt when serious.It has been proposed that directly that the heat dispersion substrate of bearing integrated is sudden and violentThe idea being exposed at outside plastic-sealed body, though good heat-transfer effect can be realized in this way, because such encapsulation is also easy to appear some problems.For example, packaging body due to be not total incapsulation encapsulation, between being easy to appear between plastic packaging material and the heat dispersion substrate of bearing integratedGap, lamination lead to integrated circuit in use, moisture is easier to immerse, and moisture infiltration is to influence its air-tightness to cause to loseThe one of the major reasons of effect.When moisture reaches IC chip surface, it can be formed on its surface one layer of conductive moisture film, and willNa+, Cl- of plastic packaging material itself are also brought into therewith, and integrated circuit at work, accelerates rotten to the chemistry of chip surface aluminium wiringErosion, the final service life for influencing integrated circuit.So this be directly exposed to the heat dispersion substrate of bearing integrated outside plastic-sealed bodyPackaging method it is although thermally conductive good, but fail always to obtain practical.Also it once it has been proposed that similar encapsulation body device, but does not solveCertainly related problem, does not have practical function, is not also applied well.
Secondly, the volume of encapsulation is larger using the packing forms of total incapsulation, the space of circuit board is not only taken up, is unfavorable forTo the development of light slimming, the cost of also increased materials.
The heat generated when how reasonably to reduce encapsulation volume, timely and effective conduction integrated circuit operation, is improvedThe thermal efficiency, encapsulated moulding are the indispensable links that must be taken into consideration.
Summary of the invention
In order to solve the above technical problems, one technical scheme adopted by the invention is that:
A kind of totally-enclosed symmetric packages lead frame is provided, carrying substrates (1) have downwards rectangular recess, put in rectangular recessIt is equipped with IC chip (2), the lead frame outer surface of carrying substrates (1) and conducting wire pin (3a, 3b) are maintained at same waterThe conducting wire pin of plane, lead frame is bent upwards, and constitutes step structure, IC chip (2) bottom and carrying substrates(1) it bonds together for combined dose (7) between, IC chip (2) connects respectively through plain conductor (4a, 4b) stretches out plastic packaging modelingExpect the conducting wire pin (3a, 3b) of colloid (6) external lead frame, there is a kind of thermally conductive, insulation guarantor on IC chip surfaceCuticula, plastic packaging plastics colloid are filled in around IC chip and lead frame, and plastic packaging plastic cement is exposed in carrying substrates bottom surfaceBody constitutes totally enclosed encapsulating structure
Preferably, heat conductive insulating elastic materials (5) are packaged on the IC chip (2) surface.
Preferably.The bonding agent (7) is elargol or scolding tin or insulation silica gel.
Preferably, the plain conductor is silver wire or copper wire.
Preferably, chip horizontal side or vertical direction in the plastic packaging plastics colloid (6) is symmetrically distributed.
Preferably, the position setting resistance glue groove of the groove of carrying substrates patch chip, prevents the excessive of conducting resinl from overflowingOut, meanwhile, in the place setting lock glue hole of Ji Dao and pin, increase the bonded area of plastic packaging glue and lead frame.
It is in contrast to the prior art, the beneficial effects of the present invention are: existing semiconductor devices heat dissipation can be solved effectivelyEffect is poor, volume is big, at high cost, the problem of improving service life, and the technical solution solved is to allow the carrying base of integrated circuitPiece directly exposes outside packaging body, and since pyrotoxin directly contacts carrying substrates, heat that integrated circuit operation generates is via holdingIt carries substrate to be directly transferred in air, or changes by the fin conductive of circuit board so good heat dissipation effect can be reachedInto the structure of lead frame, change air-tightness between scattered plastic packaging material and the carrying substrates of integrated circuit, to chip before plastic packaging processA kind of thermally conductive, insulation elastic material (composite material being made of high molecular material and some inorganic material, such as silicon on surface pointGlue etc.), after roasting procedure, a kind of flexible, sealing protective film is formed in chip surface, can effectively prevent aqueous vaporBe immersed in chip surface, also the problem of packaging air tightness difference caused by such encapsulation of very good solution, encapsulates by wrapping entirelyThe packing forms of envelope are changed to the packing forms of half encapsulating, not only reduce the volume of packaging body, also save the cost of materials, according toThis, structure of the invention is that carrying substrates have downwards rectangular recess, and IC chip is placed in rectangular recess, carries baseThe lead frame outer surface of piece and conducting wire pin are maintained at same level, and the conducting wire pin of lead frame is bent upwards, and constituteStep structure bonds together for combined dose between IC chip bottom and carrying substrates, and IC chip is through goldBelong to conducting wire and connect the conducting wire pin for stretching out the lead frame outside plastic packaging plastic cement body respectively, IC chip surface has one kind to leadHeat, the protective film to insulate, plastic packaging plastics colloid are filled in around IC chip and lead frame, and carrying substrates bottom surface is exposedPlastic packaging plastics colloid constitutes totally enclosed encapsulating structure, and the configuration of the present invention is simple, good heat dissipation effect is at low cost, service lifeLong, economic and social benefit is significant.
Detailed description of the invention
Fig. 1 structure of the invention sectional front view.
Fig. 2 is that the resistance glue groove structural plan diagram of lead frame of the present invention is intended to.
Specific embodiment
Below in conjunction with the embodiment of the present invention and attached drawing, technical solution in the embodiment of the present invention carries out clear, completeGround description, it is clear that the described embodiments are merely a part of the embodiments of the present invention, instead of all the embodiments.Based on thisEmbodiment in invention, every other reality obtained by those of ordinary skill in the art without making creative effortsExample is applied, shall fall within the protection scope of the present invention.
As shown in attached drawing 1, carrying substrates 1 of the present invention have downwards rectangular recess, are placed with ic core in rectangular recessPiece 2, the lead frame outer surface of carrying substrates 1 and conducting wire pin 3a, 3b are maintained at same level, and the conducting wire of lead frame drawsFoot is bent upwards, and is constituted step structure, is bonded in one for combined dose 7 between 2 bottom of IC chip and carrying substrates 1It rises, the conducting wire that IC chip 2 connects the lead frame stretched out outside plastic packaging plastics colloid 6 through plain conductor 4a, 4b respectively drawsThere is a kind of thermally conductive, insulation protective film on foot 3a, 3b, IC chip surface, and plastic packaging plastics colloid is filled in ic coreAround piece and lead frame, plastic packaging plastics colloid is exposed in carrying substrates bottom surface, constitutes totally enclosed encapsulating structure.
In order to guarantee using effect, heat conductive insulating elastic materials 5 are packaged on described 2 surface of IC chip；Described bonding agent 7 is elargol or scolding tin etc., it is contemplated that some integrated circuits need and external insulation, and heating conduction also can be selectedGood but nonconducting insulating silicon glue connection；Described plain conductor is gold thread (AuWire) or copper wire (Cu Wire), to reachWith extraneous electric connection；Described heat conductive insulating elastic materials 5 are high molecular material and the composite wood that inorganic material formsMaterial, such as silica gel after toasted, form a kind of flexible, sealing protective film in chip surface, can effectively prevent aqueous vaporIt is immersed in chip surface, the problem of packaging air tightness difference caused by such encapsulation of very good solution, therefore also have goodElasticity can preferably protect chip, prevent certain integrated circuits during plastic packaging, due to plastic packaging material, elargol, lead frameThe thermal expansion coefficient of the unlike materials such as frame, silicon crystal is different, generates chip cracks caused by different stress at high temperatureThe yields of encapsulation procedure also can be improved in problem；Then by plastic packaging material adhesive body in a manner of pressing mold (molding) be filled in it is integratedAround circuit chip and lead frame, clubfoot part is all encapsulated in plastic-sealed body, the conducting wire pin of lead frame exposes oneDivide outside plastic-sealed body, in favor of the welding of circuit board.Generally use the plastic packaging material with certain thermal conductivity, such as epoxy resin modelingEnvelope material (epoxy moldingcompound, EMC).The outer surface of lead frame, the i.e. bottom of the rectangle of lead frame carrying substratesFace exposes except plastic-sealed body, the packing forms of half encapsulation of 89 mounted type of SOT is similar to after plastic packaging molding, so as to integrated electricityRoad chip can be directly over lead frame carrying substrates and outwardly realize good conduction；Then the formed product good to plastic packaging,Remove extra carrier part.
Increase the bonded area of plastic packaging glue, and improves the important step of reliability, as shown in attached drawing 2, the carryingSubstrate pastes the position setting resistance glue groove of the groove of chip, prevents the excessive spilling of conducting resinl, meanwhile, in the place of Ji Dao and pinSetting lock glue hole, increases the bonded area of plastic packaging glue and lead frame, in addition, for the heat dissipation flake products that the back side is exposed, oftenGroove and aperture cannot be used, can be designed in substrate front using pit, increases surface area, makes plastic packaging glue preferably and leadFrame combines.
Chip horizontal side or vertical direction in the plastic packaging plastics colloid (6) are symmetrically distributed, all in plastic-sealed bodySymmetric design, these structures can influence the plastic packaging material on product different directions distribution, the consistent production of elder brother's directional spredingProduct internal stress is symmetrical, and the integrated stress of product is smaller；The asymmetric product stress of all directions is asymmetric, product integrally byThe stress arrived is bigger, influences the reliability of product.
Leadframe leads lead foot is improved through the invention, preferably solves and carrying heat dispersion substrate is exposed into packaging bodyBad problem is combined between its plastic packaging material epoxy resin being likely to occur outside and carrying heat dispersion substrate, makes to reach secured between itCombination, to reach favorable sealing property after encapsulated moulding.The volume of packaging body can be reduced, after encapsulated moulding conducive to partly leadingDevelopment of the body to small slimming.
The present invention reduces packaging body after being advantageous in that the form that integrated circuit is changed to half encapsulation by full packing formsVolume saves the cost of materials；Radiating efficiency is also effectively increased under the premise of meeting application requirement and promotes productYields because present invention eliminates the processes of conventional package pin brake forming, can also save customization molding equipment cost andEliminate this procedure of pin brake forming.
The above description is only an embodiment of the present invention, is not intended to limit the scope of the invention, all to utilize this hairEquivalent structure or equivalent flow shift made by bright description is applied directly or indirectly in other relevant technology necksDomain is included within the scope of the present invention.